/Engine/Source/Runtime/Engine/Classes/GameFramework/Actor.h
When receiving a hit from another object's movement (bSelfMoved is false), the directions of 'Hit.Normal' and 'Hit.ImpactNormal' will be adjusted to indicate force from the other object against this object.
virtual void NotifyHit ( class [UPrimitiveComponent](API\Runtime\Engine\Components\UPrimitiveComponent) * MyComp, [AActor](API\Runtime\Engine\GameFramework\AActor) * Other, class [UPrimitiveComponent](API\Runtime\Engine\Components\UPrimitiveComponent) * OtherComp, bool bSelfMoved, FVector HitLocation, FVector HitNormal, FVector NormalImpulse, const [FHitResult](API\Runtime\Engine\Engine\FHitResult) & Hit )